WO2025205803A1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

Provided are a liquid crystal alignment agent which has a high voltage holding ratio even when a negative-type liquid crystal is used, can obtain a liquid crystal alignment film having a small amount of accumulated charge, and is excellent in printability, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element using the liquid crystal alignment film.　The liquid crystal alignment agent contains a diamine (A) represented by formula (D_A) and one or more kinds of polymers (P).　Polymer (P): a polymer selected from the group consisting of a polyimide precursor obtained by using a tetracarboxylic acid derivative component and a diamine component substantially not containing a diamine (A) represented by formula (D_A), and a polyimide which is an imidation product of the polyimide precursor. (D_A): Z-NH-Ar₁-X₁-(R₁-L)_n-R₂-X₂-Ar₂-NH-Z

Description

Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display device equipped with the liquid crystal alignment film.

Liquid crystal display elements are widely used in a variety of applications, from small devices such as mobile phones and smartphones to relatively large devices such as televisions and monitors. A variety of driving methods have been developed, each with different electrode structures and the physical properties of the liquid crystal molecules used. Known examples of liquid crystal display elements include twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), and fringe field switching (FFS). These liquid crystal display elements generally have a liquid crystal alignment film, which is essential for controlling the alignment of the liquid crystal molecules. Polyamic acid and its derivatives (such as polyimide) are commonly used materials for liquid crystal alignment films.

Liquid crystal display elements are required to have high display quality, and Patent Document 1 discloses a composition for a liquid crystal alignment film containing an aromatic diamine such as 1,5-bis(4-aminophenoxy)pentane. Patent Document 2 also discloses a diamine in which two aromatic groups are linked to an alkylene ester chain via an ether bond, and a liquid crystal alignment agent containing a polyamic acid or a derivative thereof obtained using the diamine as a raw material.
Furthermore, in order to improve contrast in IPS-type, FFS-type, and other liquid crystal display elements, the use of negative liquid crystals has been investigated (Patent Document 3).

Japanese Patent Publication No. 06-194670 WO2022/220199 publication WO2016/152928 publication

A liquid crystal display element generally includes a liquid crystal layer sandwiched between an element substrate and a color filter substrate, pixel electrodes and a common electrode that apply an electric field to the liquid crystal layer, a liquid crystal alignment film that controls the orientation of liquid crystal molecules in the liquid crystal layer, and thin film transistors (TFTs) that switch electrical signals supplied to the pixel electrodes.
In recent years, large-screen, high-definition liquid crystal display elements have become mainstream, and display element standards with increased pixel counts, such as 4K and 8K, are being created. Liquid crystal alignment films are required to have the property of ensuring a uniform film thickness even over uneven surfaces on substrates equipped with TFTs, and liquid crystal alignment agents with better printability than conventional liquid crystal alignment agents are required.
The present inventors have conducted studies and found that when a coating test is carried out using the liquid crystal aligning agent disclosed in Patent Document 2, unevenness (uneven film thickness) is likely to occur on the coating film surface.
Therefore, in order to suppress the film thickness unevenness, we focused on a liquid crystal alignment agent containing a diamine. However, it became clear that when a negative liquid crystal was applied to a liquid crystal display element prepared using this liquid crystal alignment agent, display defects such as image sticking (image sticking of sections and lines), unevenness, or smearing were likely to occur. To suppress these display defects, a liquid crystal alignment film with excellent voltage holding ratio was required.

In addition, in IPS, FFS, and other liquid crystal display elements, not only is static electricity prone to build up within the liquid crystal cell, but the application of asymmetric voltages generated by driving can also cause charge to build up within the liquid crystal cell. These accumulated charges can disrupt the alignment of the liquid crystal or affect the display as afterimages, significantly reducing the display quality of the liquid crystal display element. For this reason, liquid crystal alignment films are required to have the property of storing a small amount of charge.

In light of the above, the object of the present invention is to provide a liquid crystal alignment agent that has excellent printability and is capable of producing a liquid crystal alignment film with a high voltage holding ratio even when using negative liquid crystals, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element using the liquid crystal alignment film. It is also to provide a liquid crystal alignment agent that produces a liquid crystal alignment film with a low amount of stored charge, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element using the liquid crystal alignment film.

As a result of intensive research into achieving the above objectives, the inventors discovered that a liquid crystal aligning agent containing a specific polymer is effective in achieving the above objectives, leading to the completion of the present invention.

The present invention is summarized as follows.
A liquid crystal aligning agent comprising a diamine (A) represented by the following formula (D _A ) and one or more polymers (P):
Polymer (P): A polymer selected from the group consisting of a polyimide precursor obtained using a tetracarboxylic acid derivative component and a diamine component that does not substantially contain a diamine (A) represented by the following formula (D _A ), and a polyimide that is an imidized product of the polyimide precursor:
Z-NH-Ar ₁ -X ₁ -(R ₁ -L) _n -R ₂ -X ₂ -Ar ₂ -NH-Z (D _A )
In formula (D _A ), Ar ₁ and Ar ₂ each independently represent a divalent aromatic group such as a divalent benzene ring, a biphenyl structure, or a naphthalene ring, and any hydrogen atom in the aromatic group may be replaced with a monovalent group.
_X1 and _X2 each independently represent a single bond, —O—, or *1-O—CO— (*1 represents a bond to _Ar1 or _Ar2 ).
_R1 and _R2 are each independently a divalent hydrocarbon group, and some of the hydrogen atoms in the divalent hydrocarbon group may be substituted with a halogen atom, a methyl group, a trifluoromethyl group, or a hydroxy group. When there are multiple _R1s , the multiple _R1s may be the same or different.
L represents -O-, -C(=O)-, -O-C(=O)-, or -C(=O)-O-. When a plurality of Ls are present, the plurality of Ls may be the same or different, provided that at least one L represents -O-C(=O)- or -C(=O)-O-.
n is an integer from 1 to 6.
Z represents a hydrogen atom or a monovalent organic group. Multiple Zs may be the same or different.
In this specification, examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc. * represents a bond.

The present invention makes it possible to obtain a liquid crystal alignment film that has a high voltage holding ratio and a small amount of accumulated charge even when using negative liquid crystals. Furthermore, it also makes it possible to obtain a liquid crystal alignment agent with excellent printability, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element using the liquid crystal alignment film.

The mechanism by which the above-mentioned effects of the present invention are achieved is not entirely clear, but it is presumed to be roughly as follows. First, it is believed that the addition of diamine in a low molecular weight state results in excellent printability. Furthermore, it is believed that the addition of diamine with high electrical resistance results in a high voltage retention rate and a small amount of accumulated charge, thereby achieving the above-mentioned effects of the invention.

1 is a schematic partial cross-sectional view showing an example of a horizontal electric field liquid crystal display element of the present invention. FIG. 10 is a schematic partial cross-sectional view showing another example of the horizontal electric field liquid crystal display element of the present invention.

The liquid crystal aligning agent of the present invention contains a diamine (A) represented by the following formula (D _A ) (hereinafter also referred to as specific diamine (A)), and one or more polymers (P):
Polymer (P): A polymer selected from the group consisting of a polyimide precursor obtained using a tetracarboxylic acid derivative component and a diamine component that does not substantially contain a diamine (A) represented by the following formula (D _A ), and a polyimide that is an imidized product of the polyimide precursor:
Z-NH-Ar ₁ -X ₁ -(R ₁ -L) _n -R ₂ -X ₂ -Ar ₂ -NH-Z (D _A )
In formula (D _A ), Ar ₁ and Ar ₂ each independently represent a divalent aromatic group such as a divalent benzene ring, a biphenyl structure, or a naphthalene ring, and any hydrogen atom in the aromatic group may be replaced with a monovalent group.
_X1 and _X2 each independently represent a single bond, —O—, or *1-O—CO— (*1 represents a bond to _Ar1 or _Ar2 ).
_R1 and _R2 are each independently a divalent hydrocarbon group, and some of the hydrogen atoms in the divalent hydrocarbon group may be substituted with a halogen atom, a methyl group, a trifluoromethyl group, or a hydroxy group. When there are multiple _R1s , the multiple _R1s may be the same or different.
L represents -O-, -C(=O)-, -O-C(=O)-, or -C(=O)-O-. When a plurality of Ls are present, the plurality of Ls may be the same or different, provided that at least one L represents -O-C(=O)- or -C(=O)-O-.
n is an integer from 1 to 6.
Z represents a hydrogen atom or a monovalent organic group. Multiple Zs may be the same or different.

<Specific diamine (A)>
The liquid crystal aligning agent of the present invention contains a specific diamine (A).
The content of the specific diamine (A) contained in the liquid crystal aligning agent of the present invention is preferably 0.1 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass of the total content of the polymer (P).
From the viewpoint of maintaining the applied voltage and suppressing accumulated charge, the content of the specific diamine (A) is more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more, per 100 parts by mass of the total content of the polymer (P).
In order to obtain a uniform coating film, the content of the specific diamine (A) is more preferably 25 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the total content of the polymer (P).
The concentration of the specific diamine (A) in the total amount of the liquid crystal aligning agent is preferably 41 mass ppm or more and 4.1×10 ³ mass ppm or less.
Furthermore, the concentration of the specific diamine (A) in the total amount of the liquid crystal aligning agent is preferably 2.1×10 ² mass ppm or more, more preferably 4.1×10 ² mass ppm or more.

In the above formula (D _A ), R ₁ and R ₂ are each independently a divalent hydrocarbon group, and examples thereof include, but are not limited to, a linear or branched alkylene group, —CH═CH—, a phenylene group, or a cyclohexylene group.
From the viewpoint of obtaining high liquid crystal alignment properties, _R1 and _R2 are preferably hydrocarbon groups having 2 to 6 carbon atoms, more preferably alkylene groups having 2 to 4 carbon atoms, and even more preferably alkylene groups having 2 or 4 carbon atoms.
A portion of the hydrogen atoms of the divalent hydrocarbon group may be substituted with a halogen atom, a methyl group, a trifluoromethyl group, or a hydroxy group, and the halogen atom substituting the hydrogen atom of the divalent hydrocarbon group is preferably a fluorine atom. When a plurality of R _1s are present, the plurality of R _1s may be the same or different.
L represents -O-, -C(=O)-, -O-C(=O)-, or -C(=O)-O-. When a plurality of Ls are present, the plurality of Ls may be the same as or different from one another. However, it is preferable that at least one L represents -O-C(=O)- or -C(=O)-O-, and at least two Ls represent -O-C(=O)- or -C(=O)-O-. n represents an integer of 1 to 6, preferably an integer of 1 to 4, more preferably an integer of 2 to 4, and even more preferably an integer of 2 or 4.

More preferred specific examples of the group "*-(R ₁ -L) _n -R ₂ -*" in the above formula (D _A ) include the following structures.
*-(CH ₂ ) _p -O-C(=O)-(CH ₂ ) _q -C(=O)-O-(CH ₂ ) _r -*,
*-(CH ₂ ) _p -C(=O)-O-(CH ₂ ) _q -O-C(=O)-(CH ₂ ) _r -*,
*-(CH ₂ ) _n1 -O-C(=O)-(CH ₂ ) _n2 -C(=O)-O-(CH ₂ ) _n3 -O-C(=O)-(CH ₂ ) _n4 -C(=O)-O-(CH ₂ ) _n5 -*,
*-(CH ₂ ) _n1 -C(=O)-O-(CH ₂ ) _n2 -O-C(=O)-(CH ₂ ) _n3 -C(=O)-O-(CH ₂ ) _n4 -O-C(=O)-(CH ₂ ) _n5 -*,
In the above structure, p, q, and r are each independently an integer of 1 to 6.
n1 to n5 are each independently an integer of 1 to 6. However, when n1 to n5 are each a divalent hydrocarbon group, the total number of carbon atoms is 20 or less.
* represents a bond.

Examples of the monovalent group substituting the hydrogen atom of the divalent aromatic group of Ar ₁ and Ar ₂ in the above formula (D _A ) include a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, a carboxy group, a hydroxy group, an alkyloxycarbonyl group having 1 to 10 carbon atoms, a cyano group, a nitro group, etc. Among these, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, or a fluoroalkoxy group having 1 to 5 carbon atoms is preferred.

Preferred examples of the divalent aromatic group represented by Ar ₁ and Ar ₂ include 1,4-phenylene, 1,3-phenylene, 2-methyl-1,4-phenylene, 2-ethyl-1,4-phenylene, 2-propyl-1,4-phenylene, 2-butyl-1,4-phenylene, 2-isopropyl-1,4-phenylene, 2-tert-butyl-1,4-phenylene, 2-methoxy-1,4-phenylene, 2-ethoxy-1,4-phenylene, 2-propoxy-1,4-phenylene, and 2-butoxy-1,4-phenylene. phenylene, 2-fluoro-1,4-phenylene, 2,3-dimethyl-1,4-phenylene, 2,6-dimethyl-1,4-phenylene, 4-methyl-1,3-phenylene, 5-methyl-1,3-phenylene, 4-fluoro-1,3-phenylene, 2,3,5,6-tetramethyl-1,4-phenylene, 4,4'-biphenylylene, 2-methyl-4,4'-biphenylylene, 2-ethyl-4,4'-biphenylylene, 2-propyl-4,4'-biphenylylene, 2-butyl-4 ,4'-biphenylylene, 2-tert-butyl-4,4'-biphenylylene, 2-methoxy-4,4'-biphenylylene, 2-ethoxy-4,4'-biphenylylene, 2-fluoro-4,4'-biphenylylene, 3-methyl-4,4'-biphenylylene, 3-ethyl-4,4'-biphenylylene, 3-propyl-4,4'-biphenylylene, 3-butyl-4,4'-biphenylylene, 3-tert-butyl-4,4'-biphenylylene, 3-methoxy-4,4'-biphenylylene biphenylylene, 3-ethoxy-4,4'-biphenylylene, 3-fluoro-4,4'-biphenylylene, 2,2'-dimethyl-4,4'-biphenylylene, 3,3'-dimethyl-4,4'-biphenylylene, 3,3'-biphenylylene, 5-methyl-3,3'-biphenylylene, 5,5'-dimethyl-3,3'-biphenylylene, 1,4-naphthylene, 1,5-naphthylene, 1,6-naphthylene, 1,7-naphthylene, 2,6-naphthylene, 2,7-naphthylene, and the like.

Examples of the monovalent organic group for Z in formula (D _A ) above include monovalent hydrocarbon groups having 1 to 6 carbon atoms, monovalent groups A obtained by replacing a methylene group of the hydrocarbon group with —O—, —S—, —CO—, —COO—, —COS—, —NR ³ —, —CO—NR ³ —, —Si(R ³ ) ₂ — (wherein R ³ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms), —SO ₂ — or the like, monovalent groups obtained by replacing at least one hydrogen atom bonded to a carbon atom of the monovalent hydrocarbon group or the monovalent group A with a halogen atom, a hydroxy group, an alkoxy group, a nitro group, an amino group, a mercapto group, a nitroso group, an alkylsilyl group, an alkoxysilyl group, a silanol group, a sulfino group, a phosphino group, a carboxy group, a cyano group, a sulfo group, an acyl group or the like, and monovalent groups having a heterocycle.
As the monovalent organic group for Z in the above formula (D _A ), an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, or a tert-butoxycarbonyl group is preferable, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group is even more preferable.
From the viewpoint of suitably achieving the effects of the present invention, Z is preferably each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or a methyl group.

Preferred examples of the above formula (D _A ) include the following formulae (d _A -1) to (d _A -10).
In addition, the hydrogen atoms on the benzene rings in the following formulae (d _A -1) to (d _A -10) may be substituted with monovalent substituents, and preferred specific examples of the substituents include the structures exemplified as the monovalent groups substituting the hydrogen atoms of the divalent aromatic groups of Ar ₁ and Ar ₂ in the above formula (D _A ).
p, q, r and n1 to n5 are the same as defined above.

<Polymer (P)>
The polymer (P) contained in the liquid crystal aligning agent of the present invention is a polymer selected from the group consisting of a polyimide precursor obtained using a tetracarboxylic acid derivative component containing a tetracarboxylic acid dianhydride and a diamine component that does not substantially contain the specific diamine (A), and a polyimide that is an imidized product of the polyimide precursor.
Here, in the present invention, the phrase "the diamine component is substantially free of the specific diamine (A)" means that the content of the specific diamine (A) in the diamine component for producing the polymer (P) is 5 parts by mass or less relative to 100 parts by mass of the total of the raw material compounds for producing the polymer (P). Furthermore, from the viewpoint of suitably obtaining the effects of the present invention, the content of the specific diamine (A) in the diamine component for producing the polymer (P) is preferably 3 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0.5 parts by mass or less relative to 100 parts by mass of the total of the raw material compounds for producing the polymer (P).

Examples of the polymer (P) include a polyimide precursor obtained using a tetracarboxylic acid derivative component containing a tetracarboxylic acid dianhydride and a diamine component containing a diamine other than the specific diamine (A) (hereinafter also referred to as "other diamine"), or a polyimide that is an imidized product of the polyimide precursor. Here, the polyimide precursor is a polymer that can be obtained by imidizing a polyamic acid, a polyamic acid ester, or the like. The polymer (P) contained in the liquid crystal aligning agent may be one type or two or more types.
The polyamic acid (P'), which is a polyimide precursor of the polymer (P), can be obtained by a polymerization reaction between a diamine component (preferably a diamine component containing other diamines) that does not substantially contain the specific diamine (A) and a tetracarboxylic acid component. The other diamines may be used alone or in combination of two or more.
The amount of the other diamines used is preferably 5 mol % or more, more preferably 10 mol % or more, and even more preferably 20 mol % or more, based on the total diamine components used in the production of polymer (P), and is preferably 95 mol % or less, more preferably 90 mol % or less, and even more preferably 85 mol % or less, based on the total diamine components used in the production of polymer (P).

Examples of other diamines include, but are not limited to, the following: The above other diamines may be used singly or in combination of two or more.
p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, m-phenylenediamine, 2,4-dimethyl-m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4' -diaminobiphenyl, 2,2'-difluoro-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 4,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,2'-diaminobiphenyl, 2,3'-diaminobiphenyl _, ), diamine (B) represented by the formula (I) (hereinafter also referred to as "specific diamine (B)", excluding those included in specific diamine (A)), 1,4-phenylenebis(4-aminobenzoate), 1,4-phenylenebis(3-aminobenzoate), 1,3-phenylenebis(4-aminobenzoate), 1,3-phenylenebis(3-aminobenzoate), bis(4-aminophenyl)terephthalate, bis(3-aminophenyl)terephthalate, bis(4-aminophenyl)isophthalate, bis(3-aminophenyl)isophthalate; diamine (B) represented by the formula (I) (hereinafter also referred to as "specific diamine (B)", excluding those included in specific diamine (A)), 1,4-phenylenebis(4-aminobenzoate), 1,4-phenylenebis(3-aminobenzoate), 1,3-phenylenebis(4-aminobenzoate), 1,3-phenylenebis(3-aminobenzoate), bis(4-aminophenyl)terephthalate, bis(4-aminophenyl)isophthalate, bis(3-aminophenyl)isophthalate; diamine (B) having a photoalignment group such as 4,4'-diaminoazobenzene or diaminotolane; Diamines: diamines having a photopolymerizable group at the end, such as 2-(2,4-diaminophenoxy)ethyl methacrylate or 2,4-diamino-N,N-diallylaniline; diamines having a radical polymerization initiator function, such as 1-(4-(2-(2,4-diaminophenoxy)ethoxy)phenyl)-2-hydroxy-2-methylpropanone and 2-(4-(2-hydroxy-2-methylpropanoyl)phenoxy)ethyl-3,5-diaminobenzoate; diamines having an amide bond, such as 4,4'-diaminobenzanilide; 1,3-bis(4-aminophenyl)urea, 1,3-bis(4-aminobenzyl)urea, ... diamines having a urea bond such as bis(4-aminophenethyl)urea; 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)diphenyl ether, 1,4-bis[4-(4-aminophenoxy)phenoxy]benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane ... ] hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(3-amino-4-methylphenyl)propane, 4,4'-diaminobenzophenone, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminobenzyl)benzene; 2,6-diaminopyridine, compounds represented by the following formula (d _n Specific diamine (C) represented by the formula (I) (hereinafter also referred to as "specific diamine (C)", excluding those included in specific diamine (A)), 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 4,4'-diamino-3,3'-dihydroxybiphenyl; 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, 4,4'-diaminobiphenyl-3-carboxylic acid, 4,4'-diaminodiphenylmethane-3-carboxylic acid, 4,4'-diaminodiphenylethane-3-carboxylic acid, 4,4'-diamino Diamines having a carboxy group such as biphenyl-3,3'-dicarboxylic acid, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid, 3,3'-diaminobiphenyl-4,4'-dicarboxylic acid, 3,3'-diaminobiphenyl-2,4'-dicarboxylic acid, 4,4'-diaminodiphenylmethane-3,3'-dicarboxylic acid, 4,4'-diaminodiphenylethane-3,3'-dicarboxylic acid, 4,4'-diaminodiphenylether-3,3'-dicarboxylic acid; 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indan-5-amine, 1-(4- diamines having the group "-N(D)-" (D represents a protecting group which is eliminated by heating and replaced with a hydrogen atom, preferably a carbamate protecting group, more preferably a tert-butoxycarbonyl group) such as those of the following formulae (5-1) to (5-8), cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestanyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, and 3,6-bis(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-6-amine; diamines having a steroid skeleton such as (aminobenzoyloxy)cholestane, diamines represented by the following formulas (V-1) to (V-2); diamines having a siloxane bond such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane; metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), diamines in which two amino groups are bonded to a group represented by any one of formulas (Y-1) to (Y-167) described in WO2018/117239, and the like.
In formula (d _AL ), Ar ₁ and Ar _1′ each independently represent a benzene ring, a biphenyl structure, or a naphthalene ring, and one or more hydrogen atoms on the benzene ring, the biphenyl structure, or the naphthalene ring may be substituted with a monovalent group.
_L1 and L1 _' each independently represent a single bond, -O-, -C(=O)-, or -O-C(=O)-. A represents _-CH2- , an alkylene group having 2 to 12 carbon atoms, or a divalent organic group in which at least one of -O-, -C(=O)-O-, and -O-C(=O)- is inserted between the carbon-carbon bonds of the alkylene group. Any hydrogen atom possessed by A may be substituted with a halogen atom.
However, when L ₁ and L _1′ in formula (d _AL ) are —O—, A represents —CH ₂ —, an alkylene group having 2 to 12 carbon atoms, or a divalent organic group formed by inserting —O— between the carbon-carbon bonds of the alkylene group.
One or more hydrogen atoms on the benzene ring, biphenyl structure, or naphthalene ring may be substituted with a monovalent group, and examples of the monovalent group include a halogen atom, an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, a fluoroalkenyl group having 2 to 3 carbon atoms, a fluoroalkoxy group having 1 to 3 carbon atoms, an alkyloxycarbonyl group having 2 to 3 carbon atoms, a cyano group, and a nitro group.
Z represents a hydrogen atom or a monovalent organic group. Multiple Zs may be the same or different.
In formula (d _n ), Y represents an aromatic ring having a nitrogen atom-containing heterocycle and an amino group represented by the group "*21-NR-*22" (where *21 and *22 represent bonds bonded to carbon atoms constituting the aromatic ring).
The carbon atom does not form a ring with the nitrogen atom to which R is attached.
R represents a hydrogen atom or a monovalent organic group, and the monovalent organic group is bonded to the nitrogen atom at a carbon atom other than the carbonyl carbon.
Z represents a hydrogen atom or a monovalent organic group. Multiple Zs may be the same or different.
(Boc represents a tert-butoxycarbonyl group.)
In the above formula (V-1), m and n are integers of 1 to 3 and satisfy the relationship 1≦m+n≦4. j is an integer of 0 or 1. ^{X 1} represents -(CH ₂ ) _a - (a is an integer of 1 to 15), -CONH-, -NHCO-, -CO-N(CH ₃ )-, -NH-, -O-, -CH ₂ O-, -CH ₂ -OCO-, -COO-, or -OCO-. R ¹ represents a monovalent group such as a fluorine atom, a fluorine atom-containing alkyl group having 1 to 10 carbon atoms, a fluorine atom-containing alkoxy group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an alkoxyalkyl group having 2 to 10 carbon atoms. When two m, n, X ¹ , or R ¹ are present, they each independently have the above definition. In the above formula (V-2), X ² represents —O—, —CH ₂ O—, —CH ₂ —OCO—, —COO—, or —OCO—.

The specific diamine (B) is preferably a diamine represented by the following formulae (d _AL -1) to (d _AL -10): 1,7-bis(4-aminophenoxy)heptane, 1,7-bis(3-aminophenoxy)heptane, 1,8-bis(4-aminophenoxy)octane, 1,8-bis(3-aminophenoxy)octane, 1,9-bis(4-aminophenoxy)nonane, 1,9-bis(3-aminophenoxy)nonane, 1,10-bis(4-aminophenoxy)decane, 1,10-bis(3-aminophenoxy)decane, 1,11-bis(4 1,11-bis(3-aminophenoxy)undecane, 1,12-bis(4-aminophenoxy)dodecane, 1,12-bis(3-aminophenoxy)dodecane, 1,2-bis(6-amino-2-naphthyloxy)ethane, 1,4-bis(6-amino-2-naphthyloxy)butane, 1,2-bis(6-amino-2-naphthyl)ethane, or 6-[2-(4-aminophenoxy)ethoxy]-2-naphthylamine.

Examples of the nitrogen atom-containing heterocycle in the above formula (d _n ) include a pyrrole ring, imidazole ring, pyrazole ring, triazole ring, pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, indole ring, benzimidazole ring, purine ring, quinoline ring, isoquinoline ring, naphthyridine ring, quinoxaline ring, phthalazine ring, triazine ring, carbazole ring, acridine ring, piperidine ring, piperazine ring, pyrrolidine ring, hexamethyleneimine ring, etc. Among these, a pyridine ring, pyrimidine ring, pyrazine ring, piperidine ring, piperazine ring, quinoline ring, carbazole ring, or acridine ring is preferred.

Examples of the monovalent organic group represented by R in the above formula (d _n ) include alkyl groups such as methyl, ethyl, and propyl; alkenyl groups such as vinyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl and methylphenyl; and alkoxy groups (e.g., methoxy and ethoxy). R is preferably a hydrogen atom or a methyl group.

Specific examples of the diamine represented by the formula (d _n ) above include 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis-(4-aminophenyl)-piperazine, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, diamines represented by the following formula (d _n -1), and diamines represented by formulas (z-1) to (z-14).

In formula (d _n -1), m1 and m1' each independently represent an integer of 1 or 2. n1 represents an integer of 1 to 3. _R1 has the same meaning as R in the amino group represented by *21-NR-*22 above.
When a plurality of R _{1 s} and m1' s are present, the plurality of R _{1 s} and m1' s may be the same or different.

Preferred specific examples of the diamine represented by the above formula (d _n -1) include diamines represented by the following formulas (Dp-1) to (Dp-6).

(Tetracarboxylic acid component of polymer (P))
When producing the polyamic acid (P'), the tetracarboxylic acid component to be reacted with the diamine component may be not only a tetracarboxylic acid dianhydride, but also a derivative of a tetracarboxylic acid dianhydride such as a tetracarboxylic acid, a tetracarboxylic acid dihalide, a tetracarboxylic acid dialkyl ester, or a tetracarboxylic acid dialkyl ester dihalide.

Examples of the tetracarboxylic acid component used in the production of the polyamic acid (P') include acyclic aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, aromatic tetracarboxylic acid dianhydrides, and derivatives thereof.
Here, the acyclic aliphatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups bonded to a chain hydrocarbon structure. However, it does not have to be composed only of a chain hydrocarbon structure, and it may also have an alicyclic structure or an aromatic ring structure as part of it.
Alicyclic tetracarboxylic acid dianhydrides are acid dianhydrides obtained by intramolecular dehydration of four carboxy groups, including at least one carboxy group bonded to an alicyclic structure. However, none of these four carboxy groups are bonded to an aromatic ring. Furthermore, they do not necessarily have to be composed solely of an alicyclic structure, and may partially contain a chain hydrocarbon structure or an aromatic ring structure.
The alicyclic tetracarboxylic acid dianhydride or derivative thereof more preferably contains a tetracarboxylic acid dianhydride or derivative thereof having at least one partial structure selected from the group consisting of a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring, and particularly preferably contains a tetracarboxylic acid dianhydride or derivative thereof having at least one structure selected from the group consisting of a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring.
The aromatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups, including at least one carboxy group bonded to an aromatic ring.
Among these, the aromatic tetracarboxylic acid derivative more preferably contains a tetracarboxylic acid dianhydride having a benzene ring or a derivative thereof.

The tetracarboxylic acid component that can be used to produce the polyamic acid (P') preferably includes the following tetracarboxylic acid dianhydrides or derivatives thereof (in the present invention, these are also collectively referred to as "specific tetracarboxylic acid derivatives (A)").
acyclic aliphatic tetracarboxylic acid dianhydrides such as 1,2,3,4-butanetetracarboxylic acid dianhydride; 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-dichloro-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-difluoro-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-bis(trifluoromethyl)-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2, 3,4-Cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3',4,4'-dicyclohexyltetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)tetrahydronaphthalene-1,2-dicarboxylic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, bicyclo[2.2 Alicyclic tetracarboxylic dianhydrides such as 2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride; pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3',4,4'-biphenylethertetracarboxylic dianhydride, 3,3',4,4'-perfluoroisopropyl ether Aromatic tetracarboxylic acid dianhydrides such as isopropylidene diphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, ethylene glycol bisanhydrotrimate, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 4,4'-carbonyldiphthalic anhydride, 4,4'-oxydi(1,4-phenylene)bis(phthalic acid) dianhydride, or 4,4'-methylenedi(1,4-phenylene)bis(phthalic acid) dianhydride; and also tetracarboxylic acid dianhydrides described in JP 2010-97188 A.

More preferred examples of the specific tetracarboxylic acid derivative (A) include 1,2,3,4-butanetetracarboxylic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-difluoro-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3- Bis(trifluoromethyl)-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3',4,4'-dicyclohexyltetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran) 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 3,3',4,4'-biphenyl ether, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 3,3',4,4'-biphenylsulfonetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 3,3',4,4'-biphenyl ether These include 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-perfluoroisopropylidenediphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, 4,4'-carbonyldiphthalic anhydride, 4,4'-oxydi(1,4-phenylene)bis(phthalic) dianhydride, 4,4'-methylenedi(1,4-phenylene)bis(phthalic) dianhydride, or derivatives thereof.

The proportion of the specific tetracarboxylic acid derivative (A) used is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 50 mol% or more, based on the total tetracarboxylic acid components used.

The liquid crystal aligning agent of the present invention may be in a form containing the following polymer (B) and/or polymer (C). The polymer (B) and the polymer (C) are forms of the polymer (P).
Polymer (B): At least one polymer (PB) selected from the group consisting of polyimide precursors obtained using a diamine component containing a specific diamine ( _B ) and polyimides which are imidized products of the polyimide precursors.
Polymer (C): At least one polymer (P _C ) selected from the group consisting of polyimide precursors obtained using a diamine component containing a specific diamine (C) and polyimides which are imidized products of the polyimide precursors.

<Polymer (B)>
The polymer (B) is a polymer (PB) selected from the group consisting of polyimide precursors obtained using a diamine component containing the specific diamine (B) and polyimides which are imidized products of the polyimide precursors. The polymer ( _B ) may be one type or two or more types of polymers ( _PB ). However, when a diamine other than the specific diamine (B) is contained as the diamine component, the specific diamine (A) is not contained.
The polymer ( _PB ) is, for example, a polyimide precursor obtained using a diamine component containing the specific diamine (B), or a polyimide which is an imidized product of the polyimide precursor. Here, the polyimide precursor is a polymer from which a polyimide can be obtained by imidizing a polyamic acid, a polyamic acid ester, or the like.

The polyamic acid ( _PB '), which is a polyimide precursor of the polymer ( _PB ), can be obtained by a polymerization reaction between a diamine component containing the specific diamine (B) and a tetracarboxylic acid component. The specific diamine (B) may be used alone or in combination of two or more.
The amount of the specific diamine (B) used is preferably 5 mol % or more, more preferably 10 mol % or more, and even more preferably 20 mol % or more, based on the total amount of the diamine components.

The diamine component used in producing the polyamic acid ( _PB ') may contain a diamine other than the specific diamine (B) (hereinafter also referred to as "other diamine 2"). When the other diamine 2 is used in combination with the specific diamine (B), the amount of the specific diamine (B) used relative to the diamine component is preferably 90 mol % or less, more preferably 80 mol % or less.
Preferred specific examples of the other diamine 2 include the diamines obtained by excluding the specific diamine (B) from the above other diamines. The other diamine 2 may also be a diamine obtained by excluding the specific diamine (C).

<Polymer (C)>
The polymer (C) is a polymer ( _PC ) selected from the group consisting of a polyimide precursor obtained using a diamine component containing the specific diamine (C) and a polyimide which is an imidized product of the polyimide precursor. One or more types of polymers may be used as the polymer ( _PC ).
However, when a diamine other than the specific diamine (C) is contained as the diamine component, the specific diamine (A) is not contained.

The polymer ( _PC ) is, for example, a polyimide precursor obtained using a diamine component containing the specific diamine (C), or a polyimide that is an imidized product of the polyimide precursor. Here, the polyimide precursor is a polymer that can be obtained by imidizing a polyamic acid, a polyamic acid ester, or the like to obtain a polyimide.

The polyamic acid (P _' ) which is the polyimide precursor of the polymer ( _P ) can be obtained by a polymerization reaction between a diamine component containing the specific diamine (C) and a tetracarboxylic acid component. The specific diamine (C) may be used alone or in combination of two or more.
The amount of the specific diamine (C) used is preferably 5 mol % or more, more preferably 10 mol % or more, even more preferably 15 mol % or more, and particularly preferably 30 mol % or more, based on the total amount of the diamine components.

The diamine component used in producing the polyamic acid (P _C ') may contain a diamine other than the specific diamine (C) (hereinafter also referred to as "other diamine 3"). When other diamine 3 is used in combination with the specific diamine (C), the amount of the specific diamine (C) used relative to the diamine component is preferably 90 mol % or less, more preferably 80 mol % or less.
When the other diamine 3 is contained as the diamine component, the specific diamine (A) is not contained.
Preferable specific examples of the other diamine 3 include the diamines obtained by excluding the specific diamine (C) from the above other diamine 1.
The other diamine 3 preferably contains a diamine having at least one group selected from the group consisting of a urea bond, an amide bond, a carboxy group, and a hydroxy group in the molecule, and at least one diamine selected from the group consisting of specific diamines (B). As the diamine component, one type of diamine may be used alone, or two or more types may be used in combination.

(Tetracarboxylic acid components of polymer ( _PB ) and polymer ( _PC ))
When producing the polyamic acid (P _B ') or polyamic acid (P _C '), the tetracarboxylic acid component to be reacted with the diamine component may be not only a tetracarboxylic acid dianhydride but also a derivative of a tetracarboxylic acid dianhydride such as a tetracarboxylic acid, a tetracarboxylic acid dihalide, a tetracarboxylic acid dialkyl ester, or a tetracarboxylic acid dialkyl ester dihalide.
Specific examples of the tetracarboxylic acid component used in producing the polyamic acid (P _B ') or polyamic acid (P _{C '} ) include the acyclic aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, aromatic tetracarboxylic acid dianhydrides, and derivatives thereof, which are exemplified for the polymer (P A '), including preferred specific examples.
The tetracarboxylic acid component used in the production of the polyamic acid (P _B ') or the polyamic acid (P _C ') more preferably contains a tetracarboxylic acid dianhydride having at least one partial structure selected from the group consisting of a benzene ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring, or a derivative thereof.
The amount of the tetracarboxylic acid derivative having the specific partial structure used is preferably 10 mol % or more _, more preferably 20 mol % or more, and even more preferably 50 mol % or more, based on the total amount of tetracarboxylic acid components used in the production of the polyamic acid (P B ') or polyamic acid (P _C ').

(Liquid crystal alignment agent)
The liquid crystal aligning agent of the present invention is, for example, a liquid composition obtained by dispersing or dissolving the polymer (P) and a polymer other than the polymer (P) that is used as needed, preferably in a suitable solvent.
The total content of the polymers contained in the liquid crystal aligning agent of the present invention can be appropriately changed depending on the thickness of the coating film to be formed, but is preferably 1% by mass or more from the viewpoint of forming a uniform and defect-free coating film, and is preferably 10% by mass or less from the viewpoint of storage stability of the solution. A particularly preferred total content of the polymers is 2 to 8% by mass.
When the liquid crystal aligning agent of the present invention contains a polymer (P), the total content of the polymer (P) is preferably 1 to 100 mass%, more preferably 10 to 100 mass%, particularly preferably 20 to 100 mass%, based on the total amount of the polymer contained in the liquid crystal aligning agent.

When the liquid crystal aligning agent of the present invention contains polymer (B) and polymer (C), the mass ratio of polymer (C) to the content of polymer (B) (content of polyimide precursor in polymer (C)/content of polyimide precursor in polymer (B)) is preferably 10/90 to 90/10, more preferably 20/80 to 90/10, and even more preferably 20/80 to 80/20.

The liquid crystal aligning agent of the present invention may contain a polymer other than polymer (P). Specific examples of other polymers include at least one polymer selected from the group consisting of polyimide precursors other than the above-mentioned polymer (P) and polyimides that are imidized products of such polyimide precursors, polysiloxane, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivative, polyacetal, polystyrene derivative, poly(styrene-maleic anhydride) copolymer, poly(isobutylene-maleic anhydride) copolymer, poly(vinyl ether-maleic anhydride) copolymer, poly(styrene-phenylmaleimide) derivative, and a polymer selected from the group consisting of poly(meth)acrylate.

Specific examples of poly(styrene-maleic anhydride) copolymers include SMA1000, SMA2000, SMA3000 (manufactured by Cray Valley Corporation) and GSM301 (manufactured by Gifu Ceramics Manufacturing Co., Ltd.), and a specific example of poly(isobutylene-maleic anhydride) copolymers includes ISOBAN-600 (manufactured by Kuraray Co., Ltd.). A specific example of poly(vinyl ether-maleic anhydride) copolymers includes Gantrez AN-139 (methyl vinyl ether maleic anhydride resin, manufactured by Ashland Corporation).
The other polymers may be used singly or in combination of two or more. The content ratio of the other polymers is preferably 90 parts by mass or less, more preferably 10 to 90 parts by mass, and still more preferably 20 to 80 parts by mass, relative to 100 parts by mass of the total of the polymers contained in the liquid crystal aligning agent.

(Production of Polyamic Acid)
Polyamic acid is produced by reacting a diamine component with a tetracarboxylic acid component in an organic solvent. The ratio of the tetracarboxylic acid component and the diamine component used in the polyamic acid production reaction is preferably such that 0.5 to 2 equivalents of the acid anhydride group of the tetracarboxylic acid component are present per equivalent of the amino group of the diamine component, and more preferably 0.8 to 1.2 equivalents. As with a typical polycondensation reaction, the closer the equivalent of the acid anhydride group of the tetracarboxylic acid component is to 1 equivalent, the higher the molecular weight of the resulting polyamic acid.
The reaction temperature in the production of polyamic acid is preferably −20 to 150° C., more preferably 0 to 100° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours. The production of polyamic acid can be carried out at any concentration, but the concentration of polyamic acid is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction can be carried out at a high concentration in the early stages, and then a solvent can be added.

Specific examples of the organic solvent include cyclohexanone, cyclopentanone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,3-dimethyl-2-imidazolidinone. Furthermore, if the polymer has high solvent solubility, solvents such as methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether can be used.

(Production of polyamic acid ester)
The polyamic acid ester can be obtained by known methods such as [I] a method of reacting the polyamic acid obtained by the above method with an esterifying agent, [II] a method of reacting a tetracarboxylic acid diester with a diamine, or [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine.

(Production of Polyimide)
Polyimides can be obtained by ring-closing (imidizing) polyimide precursors such as the polyamic acids or polyamic acid esters. The imidization ratio in this specification refers to the ratio of imide groups to the total amount of imide groups derived from tetracarboxylic dianhydrides or their derivatives and carboxyl groups (or their derivatives). The imidization ratio does not necessarily have to be 100% and can be adjusted as desired depending on the application and purpose.

Methods for imidizing the polyimide precursor include thermal imidization, in which a solution of the polyimide precursor is heated as is, and catalytic imidization, in which a catalyst is added to a solution of the polyimide precursor.
When the polyimide precursor is thermally imidized in a solution, the temperature is preferably 100 to 400°C, more preferably 120 to 250°C, and it is preferable to carry out the imidization while removing water produced by the imidization reaction from the system.

Catalytic imidization of polyimide precursors can be carried out by adding a basic catalyst and an acid anhydride to a solution of the polyimide precursor and stirring at -20 to 250°C, preferably 0 to 180°C. The amount of basic catalyst is 0.5 to 30 molar times, preferably 2 to 20 molar times, the amount of amic acid groups, and the amount of acid anhydride is 1 to 50 molar times, preferably 3 to 30 molar times, the amount of amic acid groups. Examples of basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Of these, pyridine is preferred because it has the appropriate basicity to promote the reaction. Examples of acid anhydrides include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride. Of these, acetic anhydride is preferred because it facilitates purification after the reaction. The imidization rate by catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

When recovering the resulting polyimide precursor or polyimide from a reaction solution of polyimide precursor or polyimide, the reaction solution can be precipitated by pouring it into a solvent. Examples of solvents used for precipitation include methanol, ethanol, isopropyl alcohol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, and water. The polymer precipitated by pouring it into the solvent can be recovered by filtration and then dried at room temperature or by heating under atmospheric or reduced pressure. Furthermore, the recovered polymer can be redissolved in an organic solvent and reprecipitated and recovered 2 to 10 times to reduce the amount of impurities in the polymer. Examples of solvents that can be used in this process include alcohols, ketones, and hydrocarbons. Using three or more solvents selected from these is preferable, as this further increases the efficiency of purification.

In producing the polyimide precursor or polyimide of the present invention, a terminal-capped polymer may be produced using a tetracarboxylic acid component containing a tetracarboxylic dianhydride or a derivative thereof, a diamine component containing the above-mentioned diamine, and an appropriate terminal-capping agent. The terminal-capping polymer has the effect of improving the film hardness of the alignment film obtained by coating and improving the adhesion properties between the sealant and the alignment film.
Examples of the terminals of the polyimide precursor or polyimide in the present invention include an amino group, a carboxy group, an acid anhydride group, or a group derived from an end-capping agent described below. The amino group, carboxy group, and acid anhydride group can be obtained by a conventional condensation reaction or by blocking the terminals with the following end-capping agents.

Examples of the end-capping agent include acid anhydrides such as acetic anhydride, maleic anhydride, nadic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, 3-(3-trimethoxysilyl)propyl)-3,4-dihydrofuran-2,5-dione, 4,5,6,7-tetrafluoroisobenzofuran-1,3-dione, and 4-ethynylphthalic anhydride; dicarbonic acid diester compounds such as di-tert-butyl dicarbonate and diallyl dicarbonate; chlorocarbonyl compounds such as acryloyl chloride, methacryloyl chloride, and nicotinic acid chloride; and aniline compounds. Examples of the amino acid residue include monoamine compounds such as phosphorus, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, and n-octylamine; and isocyanates having an unsaturated bond such as ethyl isocyanate, phenyl isocyanate, naphthyl isocyanate, or 2-acryloyloxyethyl isocyanate and 2-methacryloyloxyethyl isocyanate.
The proportion of the end-capping agent used is preferably 0.01 to 20 parts by mole, and more preferably 0.01 to 10 parts by mole, per 100 parts by mole of the total of the diamine components used.

The weight-average molecular weight (Mw) of the polyimide precursor and polyimide, measured by gel permeation chromatography (GPC) in terms of polyethylene glycol oxide, is preferably 1,000 to 500,000, more preferably 2,000 to 300,000, and even more preferably 10,000 to 50,000. Furthermore, the molecular weight distribution (Mw/Mn), expressed as the ratio of Mw to the number-average molecular weight (Mn) in terms of polyethylene glycol oxide measured by GPC, is preferably 15 or less, and more preferably 10 or less. Having the molecular weight within this range ensures good liquid crystal alignment in liquid crystal display elements.

The organic solvent contained in the liquid crystal aligning agent according to the present invention is not particularly limited as long as it dissolves the polymer (P) uniformly. Examples include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N,N-dimethylpropionamide, tetramethylurea, N,N-diethylformamide, N,N-diethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-diisopropyl ether, methyl ethyl ketone, methyl methyl ether, methyl ethyl ketone, methyl ethyl ether, methyl methyl ether ... Examples of suitable solvents include methylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(t-butyl)-2-pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone (collectively referred to as "good solvents"). Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, and γ-butyrolactone are preferred. The content of the good solvent is preferably 20 to 99% by mass, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass, of the total solvent contained in the liquid crystal alignment agent.

Furthermore, the organic solvent contained in the liquid crystal alignment agent is preferably a mixed solvent that combines the above-mentioned solvent with a solvent (also called a poor solvent) that improves the coatability and surface smoothness of the coating film when applying the liquid crystal alignment agent. Specific examples of poor solvents are listed below, but are not limited to these. The content of the poor solvent is preferably 1 to 80 mass % of the total solvent contained in the liquid crystal alignment agent, more preferably 10 to 80 mass %, and particularly preferably 20 to 70 mass %. The type and content of the poor solvent are selected appropriately depending on the application device, application conditions, application environment, etc. of the liquid crystal alignment agent.

Examples of poor solvents include diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, and 3-ethoxybutyl ether. Acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, 2-(2-butoxyethoxy)-1 -propanol, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monopropyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, Examples include n-butyl acetate, propylene glycol monoethyl ether acetate, cyclohexyl acetate, 4-methyl-2-pentyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), and (1S,5R)-6,8-dioxabicyclo[3.2.1]octan-4-one.

Among these, diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, and diisobutyl ketone are preferred.

Preferred solvent combinations of good and poor solvents include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and propylene glycol diacetate, N,N-dimethyl lactamide and diisobutyl ketone, and N-methyl-2-pyrrolidone N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate ester, N-ethyl-2-pyrrolidone and dipropylene glycol dimethyl ether, N,N-dimethyl lactamide and ethylene glycol monobutyl ether, N,N-dimethyl lactamide and propylene glycol diacetate, N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone, diethylene glycol monoethyl ether and butyl cellosolve acetate, N-methyl-2-pyrrolidone, diethylene glycol monomethyl ether and butyl cellosolve acetate, N,N-dimethyl lactamide and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone and γ-butyro Lactone, 4-hydroxy-4-methyl-2-pentanone, and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone, and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and diisobutyl ketone, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether pentanone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol dimethyl ether, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisobutyl ketone, N-methyl- 2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutylcarbinol, N-methyl-2-pyrrolidone, γ-butyrolactone, and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, diethylene glycol diethyl ether ethyl ether and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether and propylene glycol diacetate, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether and diisobutyl ketone, N-ethyl-2-pyrrolidone, γ-butyrolactone and diisobutyl ketone, N-ethyl-2-pyrrolidone, N,N-dimethyl lactamide and diisobutyl ketone, N-methyl-2-pyrrolidone, ethylene glycol monobutyl ether and ethylene glycol monobutyl ether acetate, γ-butyrolactone and ethylene glycol monobutyl ether acetate Examples include ethylene glycol monobutyl ether acetate and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, ethylene glycol monobutyl ether acetate and propylene glycol dimethyl ether, N-methyl-2-pyrrolidone, 4-methyl-2-pentyl acetate and ethylene glycol monobutyl ether, N-ethyl-2-pyrrolidone, cyclohexyl acetate and 4-hydroxy-4-methyl-2-pentanone, cyclohexanone and propylene glycol monomethyl ether, cyclopentanone and propylene glycol monomethyl ether, and N-methyl-2-pyrrolidone, cyclohexanone and propylene glycol monomethyl ether.

(Liquid crystal alignment agent)
The liquid crystal aligning agent of the present invention may contain, in addition to the diamine (A), the polymer (P), the polymer other than the polymer (P), and the organic solvent, other components (hereinafter also referred to as additive components). Examples of such additive components include at least one crosslinking compound selected from the group consisting of a crosslinking compound having at least one substituent selected from an oxiranyl group, an oxetanyl group, a blocked isocyanate group, an oxazoline group, a cyclocarbonate group, a hydroxy group, and an alkoxy group, and a crosslinking compound having a polymerizable unsaturated group, a functional silane compound, a metal chelate compound, a curing accelerator, a surfactant, an antioxidant, a sensitizer, a preservative, and a compound for adjusting the dielectric constant or electrical resistance of the resulting liquid crystal alignment film.

Specific preferred examples of the crosslinkable compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, bisphenol A type epoxy resins such as Epikote (registered trademark) 828 (manufactured by Mitsubishi Chemical Corporation), bisphenol F type epoxy resins such as Epikote 807 (manufactured by Mitsubishi Chemical Corporation), hydrogenated bisphenol A type epoxy resins such as YX-8000 (manufactured by Mitsubishi Chemical Corporation), and biphenyl skeleton-containing epoxy resins such as YX6954BH30 (manufactured by Mitsubishi Chemical Corporation). epoxy resins, phenol novolac epoxy resins such as EPPN-201 (manufactured by Nippon Kayaku Co., Ltd.), (o, m, p-)cresol novolac epoxy resins such as EOCN-102S (manufactured by Nippon Kayaku Co., Ltd.), triglycidyl isocyanurates such as TEPIC (registered trademark) (manufactured by Nissan Chemical Industries, Ltd.), alicyclic epoxy resins such as CELLOXIDE (registered trademark) 2021P (manufactured by Daicel Chemical Industries, Ltd.), N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3 -bis(N,N-diglycidylaminomethyl)cyclohexane or a compound containing a tertiary nitrogen atom, such as N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, or a compound having two or more oxiranyl groups, such as tetrakis(glycidyloxymethyl)methane; a compound having two or more oxetanyl groups, such as those described in paragraphs [0170] to [0175] of WO 2011/132751; Coronate (registered trademark) Compounds having a blocked isocyanate group such as AP Stable M, Coronate 2503, 2515, 2507, 2513, 2555, Millionate (registered trademark) MS-50 (all manufactured by Tosoh Corporation), Takenate (registered trademark) B-830, B-815N, B-820NSU, B-842N, B-846N, B-870N, B-874N, B-882N (all manufactured by Mitsui Chemicals, Inc.); 2,2'-bis(2-oxazoline), 2,2'-bis(4-methyl-2-oxo ... compounds having an oxazoline group such as n,n,n',n'-tetrakis(2-hydroxyethyl)adipamide, 2,2-bis(4-oxazoline), 2,2'-bis(5-methyl-2-oxazoline), 1,2,4-tris-(2-oxazolinyl-2)-benzene, and EPOCROS (registered trademark) (manufactured by Nippon Shokubai Co., Ltd.); compounds having a cyclocarbonate group described in paragraphs [0025] to [0030] and [0032] of WO2011/155577; Compounds having a hydroxy group or an alkoxy group, such as 2,2-bis(4-hydroxy-3,5-dimethoxymethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dihydroxymethylphenyl)-1,1,1,3,3,3-hexafluoropropane; and compounds represented by glycerin mono(meth)acrylate, glycerin di(meth)acrylate (1,2-, 1,3-dimer mixture), glycerin tris(meth)acrylate, glycerol 1,3-diglycerolate di(meth)acrylate, pentaerythritol tri(meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, pentaethylene glycol mono(meth)acrylate, and hexaethylene glycol mono(meth)acrylate.
The content of the crosslinkable compound is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, based on 100 parts by mass of the polymer component contained in the liquid crystal aligning agent.

Examples of compounds for adjusting the dielectric constant and electrical resistance include monoamines having a nitrogen-containing aromatic heterocycle, such as 3-picolylamine. The content of the monoamine having a nitrogen-containing aromatic heterocycle is preferably 0.1 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

Preferred specific examples of the above functional silane compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidoxypropylmethyldimethoxysilane. Examples of functional silane compounds include silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris(3-trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane. The content of the functional silane compound is preferably 0.1 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

The solid content concentration in the liquid crystal aligning agent (the ratio of the total mass of the components other than the solvent of the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, etc., and is preferably 1 to 10 mass%.
The particularly preferred range of solid content concentration varies depending on the method used when applying the liquid crystal alignment agent to the substrate. For example, when using a spin coating method, a solid content concentration of 1.5 to 4.5 mass% is particularly preferred. When using a printing method, a solid content concentration of 3 to 9 mass% is particularly preferred, thereby resulting in a solution viscosity of 12 to 50 mPa·s. When using an inkjet method, a solid content concentration of 1 to 5 mass% is particularly preferred, thereby resulting in a solution viscosity of 3 to 15 mPa·s. The temperature when preparing the polymer composition is preferably 10 to 50°C, more preferably 20 to 30°C.

(Liquid crystal alignment film and liquid crystal display element)
The liquid crystal display element according to the present invention includes a liquid crystal alignment film formed using the liquid crystal aligning agent. The operation mode of the liquid crystal display element is not particularly limited, and it can be applied to various operation modes, such as TN type, STN type, vertical alignment type (including VA-MVA type, VA-PVA type, etc.), in-plane switching type (IPS type, FFS type), and optically compensated bend type (OCB type).

The liquid crystal display element of the present invention can be manufactured, for example, by a method including the following steps (1) to (4), a method including steps (1) to (2) and (4), a method including steps (1) to (3), (4-2) and (4-4), or a method including steps (1) to (3), (4-3) and (4-4).

<Step (1): Step of applying liquid crystal alignment agent onto substrate>
In the step (1), a liquid crystal aligning agent is applied onto a substrate. Specific examples of the step (1) are as follows.
A liquid crystal alignment agent is applied to one side of a substrate having a patterned transparent conductive film by an appropriate application method, such as a roll coater method, spin coating method, printing method, or inkjet method. The substrate material is not particularly limited as long as it is highly transparent, and glass, silicon nitride, and plastics such as acrylic and polycarbonate can be used. In addition, in a reflective liquid crystal display device, an opaque material such as a silicon wafer can be used for only one substrate. In this case, a light-reflecting material such as aluminum can also be used for the electrode. Furthermore, when manufacturing an IPS or FFS liquid crystal display device, a substrate having an electrode made of a comb-shaped patterned transparent conductive film or metal film and an opposing substrate having no electrode are used. The transparent conductive film can be formed by a known method using, for example, indium tin oxide (ITO), indium zinc oxide (IZO), or a mixture thereof.

Methods for applying the liquid crystal alignment agent to a substrate and forming a film include screen printing, offset printing, flexographic printing, inkjet printing, and spray printing. Among these, application and film formation using the inkjet method are preferred.

<Step (2): Step of baking the applied liquid crystal alignment agent>
In the step (2), the liquid crystal alignment agent applied to the substrate is baked to form a film. Specific examples of the step (2) are as follows.
After applying the liquid crystal aligning agent to the substrate in step (1), the solvent can be evaporated or the polyamic acid can be thermally imidized using a heating means such as a hot plate, a hot air circulation oven, or an IR (infrared) oven. The drying and baking steps after applying the liquid crystal aligning agent can be performed at any temperature and for any time, and may be performed multiple times. The temperature at which the liquid crystal aligning agent is baked can be, for example, 40 to 180°C. To shorten the process, the baking can be performed at 40 to 150°C. The baking time is not particularly limited, but examples include 1 to 10 minutes or 1 to 5 minutes. When thermally imidizing the polyamic acid, a baking step at, for example, 150 to 300°C or 150 to 250°C may be added after the above step. The baking time is not particularly limited, but examples include 5 to 40 minutes or 5 to 30 minutes.
If the film-like material after baking is too thin, the reliability of the liquid crystal display device may decrease, so the film thickness is preferably 5 to 300 nm, more preferably 10 to 200 nm.

<Step (3): Step of subjecting the film obtained in step (2) to alignment treatment>
Step (3) is a step of optionally performing an alignment treatment on the film obtained in step (2). That is, in horizontal alignment type liquid crystal display devices such as IPS mode or FFS mode, the coating film is subjected to an alignment ability imparting treatment. On the other hand, in vertical alignment type liquid crystal display devices such as VA mode or PSA mode, the formed coating film can be used as a liquid crystal alignment film as is, but the coating film may also be subjected to an alignment ability imparting treatment. Examples of alignment treatment methods for liquid crystal alignment films include rubbing treatment and photo-alignment treatment. Examples of photo-alignment treatment methods include irradiating the surface of the film with polarized radiation in a certain direction and, optionally, performing a heat treatment at a temperature preferably of 150 to 250°C to impart liquid crystal alignment (also referred to as liquid crystal alignment ability). As the radiation, ultraviolet light or visible light having a wavelength of 100 to 800 nm can be used. Among these, ultraviolet light having a wavelength of 100 to 400 nm is preferred, and more preferably 200 to 400 nm is more preferred.

The radiation dose is preferably 1 to 10,000 mJ/ ^cm² , more preferably 100 to 5,000 mJ/ ^cm² . When irradiating with radiation, the substrate having the film-like material may be irradiated while being heated at 50 to 250°C in order to improve the liquid crystal alignment. The liquid crystal alignment film produced in this manner can stably align liquid crystal molecules in a fixed direction.
Furthermore, the liquid crystal alignment film irradiated with polarized radiation by the above method can be contact-treated with water or a solvent, or the liquid crystal alignment film irradiated with radiation can be heat-treated.

The solvent used in the contact treatment is not particularly limited, as long as it dissolves the decomposition products produced from the film-like material by irradiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. One type of solvent may be used, or two or more types may be used in combination.

The temperature for heat treatment of the coating film irradiated with the above radiation is preferably 50 to 300°C, and even more preferably 120 to 250°C. The heat treatment time is preferably 1 to 30 minutes.

<Step (4): Step of Producing Liquid Crystal Cell>
Two substrates on which the liquid crystal alignment film is formed are prepared as described above, and a liquid crystal composition is placed between the two substrates arranged opposite to each other. Specifically, the following two methods can be mentioned.
In the first method, two substrates are placed opposite each other with a gap (cell gap) between them so that their liquid crystal alignment films face each other, and then the peripheries of the two substrates are bonded together using a sealant. A liquid crystal composition is injected into the substrate surfaces and the cell gap defined by the sealant so that it comes into contact with the film surface, and the injection hole is then sealed.

The second method is called the ODF (One Drop Fill) method. For example, a UV-curable sealant is applied to a predetermined location on one of two substrates on which a liquid crystal alignment film has been formed, and a liquid crystal composition is then dropped onto several predetermined locations on the liquid crystal alignment film surface. The other substrate is then attached so that the liquid crystal alignment film faces the other substrate, and the liquid crystal composition is spread over the entire surface of the substrate and brought into contact with the film surface. Next, the entire surface of the substrate is irradiated with UV light to cure the sealant. In either method, it is desirable to further heat the substrate to a temperature at which the liquid crystal composition is in an isotropic phase, and then slowly cool it to room temperature to remove flow alignment that occurs during liquid crystal filling.
When the coating films are subjected to rubbing treatment, the two substrates are placed opposite each other so that the rubbing directions of the coating films are at a predetermined angle, for example, perpendicular or anti-parallel to each other.
Examples of sealing agents that can be used include epoxy resins containing a curing agent and aluminum oxide spheres as spacers. The liquid crystal composition is not particularly limited and may be a composition containing at least one liquid crystal compound (liquid crystal molecules), such as a liquid crystal composition exhibiting a nematic phase (hereinafter also referred to as nematic liquid crystal), a liquid crystal exhibiting a smectic phase, or a liquid crystal composition exhibiting a cholesteric phase. Nematic liquid crystals are preferred. Various liquid crystal compositions with positive or negative dielectric anisotropy can also be used. Hereinafter, a liquid crystal composition with positive dielectric anisotropy will be referred to as a positive liquid crystal, and a liquid crystal composition with negative dielectric anisotropy will be referred to as a negative liquid crystal.
The liquid crystal composition may contain a liquid crystal compound having a fluorine atom, a hydroxy group, an amino group, a fluorine atom-containing group (e.g., a trifluoromethyl group), a cyano group, an alkyl group, an alkoxy group, an alkenyl group, an isothiocyanate group, a heterocycle, a cycloalkane, a cycloalkene, a steroid skeleton, a benzene ring, or a naphthalene ring, or may contain a compound having two or more rigid moieties (mesogenic skeletons) that exhibit liquid crystallinity within the molecule (e.g., a bimesogenic compound in which two rigid biphenyl structures or terphenyl structures are linked by an alkyl group).
The liquid crystal composition may further contain an additive from the viewpoint of improving the liquid crystal alignment property, such as a photopolymerizable monomer having a polymerizable group, an optically active compound (e.g., S-811 manufactured by Merck Ltd.), an antioxidant, an ultraviolet absorber, a dye, an antifoaming agent, a polymerization initiator, or a polymerization inhibitor.
Examples of the positive liquid crystal include ZLI-2293, ZLI-4792, MLC-2003, MLC-2041, MLC-3019, and MLC-7081 manufactured by Merck.
Examples of negative liquid crystals include MLC-6608, MLC-6609, MLC-6610, MLC-7026, and MLC-7026-100 manufactured by Merck Co., Ltd., and NA-1559 manufactured by DIC Corporation.
Furthermore, an example of a liquid crystal containing a compound having a polymerizable group is MLC-3023 manufactured by Merck.

The liquid crystal aligning agent of the present invention is also preferably used for a liquid crystal display element (PSA type liquid crystal display element) which has a liquid crystal layer between a pair of substrates provided with electrodes, and is produced through a process of disposing a liquid crystal composition containing a polymerizable compound which is polymerized by at least one of active energy rays and heat between the pair of substrates, and polymerizing the polymerizable compound by at least one of irradiation with active energy rays and heating while applying a voltage between the electrodes.
The liquid crystal aligning agent of the present invention is also preferably used for a liquid crystal display element (SC-PVA mode liquid crystal display element) which has a liquid crystal layer between a pair of substrates provided with electrodes, and is produced through a process of disposing a liquid crystal alignment film containing a polymerizable group that is polymerized by at least one of active energy rays and heat between the pair of substrates, and applying a voltage between the electrodes.

<Step (4-2): In the case of a PSA type liquid crystal display element>
The method is carried out in the same manner as in (4) above, except that a liquid crystal composition containing a polymerizable compound is injected or dropped. Examples of the polymerizable compound include a polymerizable compound having one or more polymerizable unsaturated groups in the molecule, such as an acrylate group or a methacrylate group.

<Step (4-3): In the case of an SC-PVA mode liquid crystal display element>
A method for producing a liquid crystal display element may be employed in which a process similar to that described in (4) above is followed by a step of irradiating with ultraviolet light, as described below. This method, similar to the production of the PSA-type liquid crystal display element, allows for the production of a liquid crystal display element with excellent response speed with a small amount of light irradiation. The compound having a polymerizable group may be a compound having one or more of the above-described polymerizable unsaturated groups in the molecule, and the content thereof is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, per 100 parts by mass of all polymer components. The polymerizable group may also be contained in a polymer used in a liquid crystal aligning agent. Examples of such polymers include polymers obtained by reacting a diamine component containing a diamine having the above-described photopolymerizable group at its terminal.

<Step (4-4): Step of irradiating with ultraviolet light>
The liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates obtained in (4-2) or (4-3) above. The voltage applied here can be, for example, 5 to 50 V DC or AC. The irradiated light can be, for example, ultraviolet light and visible light containing light with a wavelength of 150 to 800 nm, but ultraviolet light containing light with a wavelength of 300 to 400 nm is preferred. Examples of light sources that can be used for the irradiated light include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. The light exposure is preferably 1,000 to 200,000 J/ ^m² , and more preferably 1,000 to 100,000 J/ ^m² .

Then, if necessary, a polarizing plate can be attached to the outer surface of the liquid crystal cell to obtain a liquid crystal display element. Examples of polarizing plates that can be attached to the outer surface of the liquid crystal cell include polarizing plates in which a polarizing film called an "H film," made by stretching and aligning polyvinyl alcohol and absorbing iodine, is sandwiched between cellulose acetate protective films, or polarizing plates made of the H film itself.

An IPS substrate, which is a comb-tooth electrode substrate used in IPS mode, has a base material, a plurality of linear electrodes formed on the base material and arranged in a comb-tooth pattern, and a liquid crystal alignment film formed on the base material so as to cover the linear electrodes.
The FFS substrate, which is a comb-tooth electrode substrate used in the FFS mode, has a base material, a surface electrode formed on the base material, an insulating film formed on the surface electrode, a plurality of linear electrodes formed on the insulating film and arranged in a comb-tooth pattern, and a liquid crystal alignment film formed on the insulating film so as to cover the linear electrodes.

FIG. 1 is a schematic partial cross-sectional view showing an example of an in-plane switching liquid crystal display element of the present invention, which is an example of an IPS mode liquid crystal display element.
In the IPS LCD element 1 illustrated in Fig. 1, liquid crystal 3 is sandwiched between a comb-shaped electrode substrate 2 having a liquid crystal alignment film 2c and a counter substrate 4 having a liquid crystal alignment film 4a. The comb-shaped electrode substrate 2 has a base material 2a, a plurality of linear electrodes 2b formed on the base material 2a and arranged in a comb-like pattern, and a liquid crystal alignment film 2c formed on the base material 2a so as to cover the linear electrodes 2b. The counter substrate 4 has a base material 4b and a liquid crystal alignment film 4a formed on the base material 4b. The liquid crystal alignment film 2c is, for example, the liquid crystal alignment film of the present invention. The liquid crystal alignment film 4c is also the liquid crystal alignment film of the present invention.
In this IPS LCD element 1, when a voltage is applied to the linear electrodes 2b, an electric field is generated between the linear electrodes 2b as indicated by electric force lines L.

FIG. 2 is a schematic partial cross-sectional view showing another example of the in-plane switching liquid crystal display element of the present invention, which is an example of an FFS mode liquid crystal display element.
In the IPS LCD element 1 illustrated in Figure 2, liquid crystal 3 is sandwiched between a comb-shaped electrode substrate 2 having a liquid crystal alignment film 2h and a counter substrate 4 having a liquid crystal alignment film 4a. The comb-shaped electrode substrate 2 has a base material 2d, a surface electrode 2e formed on the base material 2d, an insulating film 2f formed on the surface electrode 2e, a plurality of linear electrodes 2g formed on the insulating film 2f and arranged in a comb-like pattern, and a liquid crystal alignment film 2h formed on the insulating film 2f so as to cover the linear electrodes 2g. The counter substrate 4 has a base material 4b and a liquid crystal alignment film 4a formed on the base material 4b. The liquid crystal alignment film 2h is, for example, a liquid crystal alignment film of the present invention. The liquid crystal alignment film 4a is also a liquid crystal alignment film of the present invention.
In this IPS LCD element 1, when a voltage is applied to the surface electrodes 2e and the linear electrodes 2g, an electric field is generated between the surface electrodes 2e and the linear electrodes 2g as indicated by electric force lines L.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The abbreviations of the compounds used and the methods for measuring the physical properties are as follows:
(organic solvent)
NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone BCS: butyl cellosolve (tetracarboxylic dianhydride)
CA-1 to CA-6: Compounds represented by the following formulas (CA-1) to (CA-6), respectively
(diamine)
DA-1 to DA-7: Compounds represented by the following formulas (DA-1) to (DA-7), respectively
(Additives)
AD-1 to AD-2: Compounds represented by the following formulas (AD-1) to (AD-2), respectively

<Viscosity measurement>
Measurement was carried out at 25°C using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL and a cone rotor TE-1 (1°34', R24).

<Measurement of molecular weight>
Measurements were carried out using the following room temperature GPC (gel permeation chromatography) apparatus under the following conditions, and Mn and Mw were calculated as polyethylene glycol oxide equivalent values.
GPC device: GPC-101 (manufactured by Resonac (formerly Showa Denko) Co., Ltd.),
Column: GPC KD-803 and GPC KD-805 (manufactured by Resonac (formerly Showa Denko)) in series;
Column temperature: 50°C,
Eluent: N,N-dimethylformamide (additives: lithium bromide monohydrate (LiBr·H ₂ O) 30 mmol/L, phosphoric acid anhydrous crystal (o-phosphoric acid) 30 mmol/L, tetrahydrofuran (THF) 10 mL/L),
Flow rate: 1.0 mL/min. Standard samples for preparing a calibration curve: TSK standard polyethylene oxide (molecular weight: approximately 900,000, approximately 150,000, approximately 100,000, and approximately 30,000) (manufactured by Tosoh Corporation) and polyethylene glycol (molecular weight: approximately 12,000, approximately 4,000, and approximately 1,000) (manufactured by Polymer Laboratory Co., Ltd.).

[Synthesis of Monomer]
DA-7 is a novel compound not previously disclosed in the literature, and the product in Monomer Synthesis Example 1 below was identified by ¹ H-NMR analysis. The analysis conditions are as follows:
Equipment: BRUKER ADVANCE III-500MHz
Measurement solvent: deuterated dimethyl sulfoxide (DMSO-d ₆ )
Reference substance: tetramethylsilane (TMS) (δ 0.0 ppm for ¹ H)

<Monomer Synthesis Example 1: Synthesis of DA-7>
2-(4-nitrophenoxy)ethanol (50.0 g, 273 mmol) was charged with THF (600 g), 4-dimethylaminopyridine (DMAP, 16.6 g, 13.6 mmol), and succinic anhydride (34.1 g, 341 mmol), and the mixture was stirred at 50°C. 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl, 59.8 g, 312 mmol) and 1,4-butanediol (11.7 g, 130 mmol) were charged into the resulting solution, and the mixture was stirred at room temperature (25°C) for 3 hours. After completion of the reaction, water (1.5 kg) was added to precipitate crystals. The solid obtained by filtration was dried to obtain crude crystals. THF (300 g) was added to the crude crystals, and the mixture was heated and stirred at 65°C. After cooling to room temperature, methanol (1.5 kg) was added and the mixture was recrystallized. The crystals were filtered off and the resulting crystals were dried to obtain DA-7-1 (yield: 60.4 g, 97.2 mmol, 75%).
¹ H-NMR (500MHz) in DMSO-d ₆ :8.21 (d, J=9.2Hz, 4H), 7.17 (d, J=9.2Hz, 4H), 4.37 (q, 8H), 3.99 (s, 4H), 2.58 (m, 8H), 1.57 (m, 4H).

To the DA-7-1 (60.3 g, 97.2 mmol) obtained above, THF (1.2 kg) was added and the mixture was purged with nitrogen. Then, carbon-supported palladium (5% Pd carbon powder (hydrated product) K type, manufactured by N.E. Chemcat Corporation) (6.0 g) was added, the mixture was purged with nitrogen again, a Tedlar bag containing hydrogen was attached, and the mixture was stirred at room temperature for 4 days. After completion of the reaction, the carbon-supported palladium was removed by passing through a membrane filter, and the filtrate was completely concentrated to precipitate crude crystals. Isopropyl alcohol (240 g) was added to the crude crystals, and the mixture was washed by stirring at room temperature. The crystals obtained after filtration were dried to obtain DA-7 (yield: 44.8 g, 79.9 mmol, 82% yield).
¹ H-NMR (500MHz) in DMSO-d ₆ :6.65 (d, J=8.9Hz, 4H), 6.50 (d, J=8.9Hz, 4H), 4.62 (s, 4H) 4.27 (m, 4H), 4.00 (m, 8H), 2.57 (m, 8H), 1.59 (m, 4H).
<Measurement of compound concentration>
Measurement was carried out using the following LC (liquid chromatography) apparatus under the following conditions, and the compound concentration in the sample was calculated from the prepared calibration curve.
LC device: 1290 Infinity II (Agilent Technologies),
Column: InertSustain C18 4.6 x 250 mm, 5 μm (GL Science),
Column temperature: 40°C,
Mobile phase: A: phosphate buffer (pH 6.8), B: acetonitrile, A/B = 40/60
Detector: PDA (wavelength 270 nm)
Flow rate: 1.0mL/min

[Synthesis of Polymer]
<Synthesis Example 1>
DA-1 (2.29 g, 8.00 mmol) and NMP (16.8 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while supplying nitrogen. CA-1 (1.69 g, 7.54 mmol) and NMP (12.4 g) were then added, and the mixture was stirred at 40°C for 18 hours to obtain a solution of polyamic acid (A-1) with a solids concentration of 12% by mass (viscosity: 225 mPa s). The Mn of this polyamic acid was 10,382, and the Mw was 32,874.
<Synthesis Example 2>
DA-2 (0.977 g, 4.00 mmol), DA-3 (0.797 g, 4.00 mmol), and NMP (10.1 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while feeding nitrogen. Thereafter, CA-2 (1.50 g, 6.00 mmol) and NMP (8.30 g) were added, and the mixture was stirred at 50 ° C. for 5 hours. Thereafter, after cooling to room temperature, CA-3 (0.494 g, 1.68 mmol) and NMP (2.80 g) were added, and the mixture was stirred at 70 ° C. for 18 hours to obtain a solution of polyamic acid (A-2) with a solids concentration of 15% by mass (viscosity: 304 mPa s). The Mn of this polyamic acid was 9,284, and the Mw was 26,834.
<Synthesis Example 3>
DA-1 (3.72 g, 13.0 mmol) and NMP (37.3 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while supplying nitrogen. After cooling to room temperature, CA-4 (2.64 g, 12.1 mmol) and NMP (9.30 g) were added, and the mixture was stirred at 50°C for 18 hours to obtain a solution of polyamic acid (A-3) with a solids concentration of 12 mass%.
<Synthesis Example 4>
DA-3 (5.58 g, 28.0 mmol), DA-4 (1.39 g, 7.01 mmol), and NMP (62.7 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while supplying nitrogen. Thereafter, CA-5 (5.08 g, 25.9 mmol) and NMP (3.80 g) were added, and the mixture was stirred at room temperature for 2 hours. Thereafter, CA-6 (2.10 g, 6.99 mmol) and NMP (13.7 g) were added, and the mixture was stirred at room temperature for 18 hours, to obtain a solution of polyamic acid (A-4) with a solids concentration of 15% by mass.
<Synthesis Example 5>
DA-5 (1.46 g, 3.50 mmol), DA-1 (1.00 g, 3.50 mmol), and NMP (18.0 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while introducing nitrogen. After that, after cooling to room temperature, CA-1 (1.48 g, 6.58 mmol) and NMP (10.8 g) were added, and the mixture was stirred at 40 ° C. for 18 hours to obtain a solution of polyamic acid (A-5) with a solids concentration of 12% by mass (viscosity: 282 mPa s). The Mn of this polyamic acid was 10,704, and the Mw was 39,144.

Table 1 shows the types and amounts of the tetracarboxylic acid components and diamine components used in Synthesis Examples 1 to 5 above. The numerical values for the tetracarboxylic acid components and diamine components in Table 1 represent the proportion (parts by mole) of each compound used relative to 100 parts by mole of the total amount of diamine components used in the synthesis of each polyamic acid.

[Preparation of liquid crystal alignment agent]
Example 1
To the solution (1.63 g) of polyamic acid (A-1) obtained in Synthesis Example 1, the solution (3.90 g) of polyamic acid (A-2) obtained in Synthesis Example 2, NMP (0.90 g), GBL (6.36 g), BCS (6.00 g), AD-1 (1 mass % GBL solution, 0.78 g), AD-2 (10 mass % NMP solution, 0.39 g), and DA-5 (0.04 g) were added, and the mixture was stirred at room temperature for 2 hours to obtain a liquid crystal aligning agent (AL-1) of the present invention.

<Examples 2 to 5 and Comparative Examples 1 to 4>
The liquid crystal aligning agent (AL-2) to (AL-5) of Examples 2 to 5 of the present invention and the liquid crystal aligning agent (AL-C1) to (AL-C4) of Comparative Examples 1 to 4 were obtained by the same operation as in Example 1, except that the type and amount of the polymer solution, solvent, and additive used were changed as shown in Table 2.

In Table 2, the values for Polymer 1, Polymer 2, Additive 1, Additive 2, and Diamine represent the proportion (parts by mass) of each polymer solid content and additive relative to 100 parts by mass of the total polymer components.

The liquid crystal alignment agents AL-1 to AL-2 of Examples 1 and 2, the liquid crystal alignment agent AL-C2 of Comparative Example 2, and the liquid crystal alignment agent AL-C4 of Comparative Example 4 contain diamine DA-5. The measurement results are shown in Table 3.
DA-5 ^*1 in Table 3 represents the content (parts by mass) of DA-5 when the total amount of the polymer components is 100 parts by mass. The lower limit of quantitation in this measurement was 9.3×10 ⁻³ (parts by mass).
DA-5 ^*2 represents the concentration (ppm by mass) of DA-5 in the total amount of the liquid crystal alignment agent. The lower limit of quantitation in this measurement was 3.8 ppm by mass.

[Fabrication of Liquid Crystal Cell]
<Preparation of Liquid Crystal Cell for Evaluating Voltage Holding Ratio>
First, a substrate with electrodes was prepared. The substrate was a glass substrate measuring 30 mm x 40 mm and 0.7 mm thick. ITO electrodes with a film thickness of 35 nm were formed on the substrate, and the electrodes were in a stripe pattern spaced 40 mm vertically and 10 mm horizontally.
Next, the liquid crystal alignment agent obtained above was filtered through a filter with a pore size of 1.0 μm and then spin-coated onto the electrode-attached substrate prepared above. The resulting solution was then dried on a hot plate at 80°C for 2 minutes and then baked in an infrared oven at 230°C for 20 minutes to form a 60 nm thick coating film, yielding a substrate with a liquid crystal alignment film. This liquid crystal alignment film was subjected to a rubbing alignment treatment (roller diameter: 120 mm, roller rotation speed: 1,000 rpm, movement speed: 20 mm/sec, indentation length: 0.4 mm) using a rayon cloth (HY-5318, manufactured by Hyperflex). The substrate was then ultrasonically cleaned in pure water for 1 minute, water droplets were removed by air blowing, and the substrate was then dried at 80°C for 10 minutes to obtain a substrate with a liquid crystal alignment film. Two substrates with this liquid crystal alignment film were prepared. Spherical spacers with a particle size of 4 μm were sprayed onto the liquid crystal alignment film surface of one of the substrates. Then, a sealant (Mitsui Chemicals XN-1500T) was printed around the periphery, leaving the liquid crystal injection port. The other substrate was then attached with the rubbing direction reversed and the film surfaces facing each other. The sealant was then cured by heating at 150°C for 60 minutes to produce an empty cell. Negative liquid crystal NA-1559 (DIC) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain a liquid crystal cell. The resulting liquid crystal cell was then heated at 120°C for 1 hour and left overnight at 23°C before being used to evaluate the voltage holding ratio.

<Fabrication of FFS Drive Liquid Crystal Cell>
A liquid crystal cell having the structure of an FFS mode liquid crystal display element was fabricated.
First, a substrate with electrodes was prepared. The substrate was a rectangular glass substrate measuring 30 mm x 50 mm and 0.7 mm thick. A solid-patterned ITO electrode constituting a common electrode was formed on the substrate as the first layer. A SiN (silicon nitride) film deposited by CVD (chemical vapor deposition) was formed on the first common electrode as the second layer. The second SiN film had a thickness of 300 nm, which served as an interlayer insulating film. A comb-shaped pixel electrode formed by patterning an ITO film as the third layer was placed on the second SiN film. Two pixels, a first pixel and a second pixel, were formed, each measuring 10 mm long and 5 mm wide. This electrode-equipped substrate had a structure in which the first common electrode and the third pixel electrode were insulated by the second SiN film.
The pixel electrode of the third layer had a comb-like shape with the central portion bent at an interior angle of 160° and multiple electrode lines, each 3 μm wide, arranged parallel to each other at intervals of 6 μm. One pixel was formed by multiple electrode lines and had a first region and a second region separated by a line connecting the bent portions.
Next, the liquid crystal alignment agent obtained above was filtered through a filter with a pore size of 1.0 μm, and then spin-coated onto the electrode-attached substrate (hereinafter referred to as the electrode substrate) and a glass substrate (hereinafter referred to as the counter substrate) having 4 μm-high columnar spacers and an ITO film formed on the backside. After drying for 2 minutes on a hot plate at 80 °C, it was baked for 20 minutes in a hot air circulating oven at 230 °C to form a coating film with a thickness of 60 nm. This coating film was subjected to a rubbing alignment treatment (roller diameter: 120 mm, roller rotation speed: 1,000 rpm, movement speed: 20 mm/sec, indentation length: 0.4 mm) using a rayon cloth (HY-5318 manufactured by Hyperflex). The substrate was then ultrasonically cleaned in pure water for 1 minute, water droplets were removed by air blowing, and the substrate was then dried for 10 minutes on a hot plate at 80 °C to obtain a substrate with a liquid crystal alignment film. The liquid crystal alignment film formed on the electrode substrate was subjected to an alignment treatment so that the direction dividing the interior angle of the pixel bend was parallel to the liquid crystal alignment direction. The liquid crystal alignment film formed on the counter substrate was also subjected to an alignment treatment so that the alignment direction of the liquid crystal on the electrode substrate was aligned with the alignment direction of the liquid crystal on the counter substrate when the liquid crystal cell was fabricated. The two substrates were combined into a pair, and a sealant (Mitsui Chemicals XN-1500T) was printed on one substrate using a dispenser. Another substrate was then attached to the other substrate, facing each other with the alignment directions of the liquid crystal alignment films aligned at 0°. The bonded substrates were then pressed together and heated for 60 minutes in a hot air circulating oven at 150°C to cure the sealant, producing an empty cell. Negative liquid crystal NA-1559 (DIC Corporation) was injected into this empty cell using a vacuum injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell. The resulting liquid crystal cell was then heated at 120°C for 1 hour and left overnight at 23°C before being used for evaluation.

[Liquid crystal cell characteristic evaluation]
The characteristics of the liquid crystal cell for evaluating the voltage holding ratio and the FFS driving liquid crystal cell prepared above were evaluated as follows.

<Evaluation of voltage holding ratio after backlight endurance test>
The liquid crystal cell for evaluating the voltage holding ratio was left for 96 hours under irradiation with a high-brightness backlight (light source: LED, brightness: 30,000 cd/ ^m2 ) with a surface temperature of 50°C. Next, a voltage of 1 V was applied to the liquid crystal cell at a temperature of 60°C for 60 μsec, and the voltage after 167 msec was measured, and the voltage holding ratio was calculated to indicate how much voltage was held. The higher the voltage holding ratio, the better the performance.
In addition, in the following Table 4, "-" in Comparative Example 4 indicates that the voltage holding ratio was not measured.

[Evaluation of charge accumulation amount by AC drive]
The liquid crystal cell prepared above was placed between two polarizing plates arranged so that their polarization axes were perpendicular to each other, and with the pixel electrode and the common electrode shorted to have the same potential, an LED backlight was irradiated from below the two polarizing plates, and the angle of the liquid crystal cell was adjusted so that the brightness of the LED backlight transmitted through the two polarizing plates was minimized. Next, an AC voltage of 60 Hz was applied to this liquid crystal cell, and the V-T curve (voltage-transmittance curve) was measured, and the AC voltage at which the relative transmittance was 23% was calculated as the driving voltage.
For the image retention evaluation, an AC voltage of 60 Hz, which resulted in a relative transmittance of 100%, was applied to the liquid crystal cell for 60 minutes. Then, an AC voltage, which resulted in a relative transmittance of 23%, was applied, and the DC voltage was swept to measure the applied voltage that minimized display flicker. The absolute value of the applied voltage that minimized display flicker was taken as the charge accumulation amount. The smaller the charge accumulation amount, the better.
The evaluation of the afterimage according to the above-mentioned method was carried out under a temperature condition in which the temperature of the liquid crystal cell was 45°C.
In addition, in the following Table 4, "-" in Comparative Examples 1 and 4 indicates that the amount of accumulated charge was not measured.

[Evaluation of Coatability]
The liquid crystal alignment agent obtained above was applied by spin coating to an ITO substrate measuring 100 mm x 100 mm and 1.1 mm thick. After drying on a hot plate at 80°C for 2 minutes, it was baked in a hot air circulating oven at 230°C for 20 minutes to obtain a substrate with a liquid crystal alignment film having a thickness of 60 nm. When this liquid crystal alignment film-coated substrate was observed with the naked eye, if the coating surface was uniform and free of unevenness, it was rated as "good," and if unevenness was visible on the coating surface, it was rated as "poor."

Table 4 shows the evaluation results of the voltage holding ratio, charge accumulation amount and coating property using each of the liquid crystal alignment agents of Examples 1 to 5 and Comparative Examples 1 to 4.
In Table 4, the numbers in parentheses for the polymer components and additive diamines represent the blending ratio (parts by mass) of each polymer solid content and additive when the total content of the polymer solid content is 100 parts by mass.

As shown in Table 4, the liquid crystal alignment film obtained from the liquid crystal alignment agent to which the specific diamine was added as an additive had a significantly improved voltage holding ratio and a significantly reduced charge accumulation amount compared to the liquid crystal alignment film obtained from the liquid crystal alignment agent to which the specific diamine was not added (Comparison between Examples 1 to 4 and Comparative Example 2, and Example 5 and Comparative Example 3).
On the other hand, when a diamine other than the specific diamine was added as an additive, the degree of improvement in the voltage holding ratio was smaller than when the specific diamine was added (Comparison between Example 1 and Comparative Example 1). Also, the liquid crystal alignment agent in which the specific diamine was incorporated into the polymer had worse coatability than the liquid crystal alignment agent to which the specific diamine was added as an additive (Comparison between Example 1 and Comparative Example 4).

Liquid crystal alignment films obtained from the liquid crystal aligning agent of the present invention are widely used in liquid crystal display elements of various operating modes, but can also be used, for example, as liquid crystal alignment films for retardation films, liquid crystal alignment films for scanning antennas and liquid crystal array antennas, or liquid crystal alignment films for transmissive/scattering liquid crystal dimming elements.

The liquid crystal display element of the present invention can be effectively applied to devices with a variety of functions, such as LCD televisions, clocks, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, and information displays.

1: In-plane switching liquid crystal display element, 2: Comb electrode substrate, 2a, 4b, 2d: Base material, 2b, 2g: Linear electrodes, 2c, 2h, 4a: Liquid crystal alignment film, 2e: Planar electrode, 2f: Insulating film, 3: Liquid crystal, 4: Counter substrate, L: Electric field lines

The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2024-052127, filed on March 27, 2024, are hereby incorporated by reference as part of the disclosure of the specification of the present invention.

Claims (12)

A liquid crystal aligning agent comprising a diamine (A) represented by the following formula (D _A ) and one or more polymers (P):
Polymer (P): A polymer selected from the group consisting of a polyimide precursor obtained using a tetracarboxylic acid derivative component and a diamine component that does not substantially contain a diamine (A) represented by the following formula (D _A ), and a polyimide that is an imidized product of the polyimide precursor:
Z-NH-Ar ₁ -X ₁ -(R ₁ -L) _n -R ₂ -X ₂ -Ar ₂ -NH-Z (D _A )
In formula (D _A ), Ar ₁ and Ar ₂ each independently represent a divalent aromatic group such as a divalent benzene ring, a biphenyl structure, or a naphthalene ring, and any hydrogen atom in the aromatic group may be replaced with a monovalent group.
_X1 and _X2 each independently represent a single bond, —O—, or *1-O—CO— (*1 represents a bond to _Ar1 or _Ar2 ).
_R1 and _R2 are each independently a divalent hydrocarbon group, and some of the hydrogen atoms in the divalent hydrocarbon group may be substituted with a halogen atom, a methyl group, a trifluoromethyl group, or a hydroxy group. When there are multiple _R1s , the multiple _R1s may be the same or different.
L represents -O-, -C(=O)-, -O-C(=O)-, or -C(=O)-O-. When a plurality of Ls are present, the plurality of Ls may be the same or different, provided that at least one L represents -O-C(=O)- or -C(=O)-O-.
n is an integer from 1 to 6.
Z represents a hydrogen atom or a monovalent organic group. Multiple Zs may be the same or different. 2. The liquid crystal aligning agent according to claim 1, wherein the group "*-(R ₁ -L) _n -R ₂ -*" in the formula (D _A ) is selected from the following structures:
*-(CH ₂ ) _p -O-C(=O)-(CH ₂ ) _q -C(=O)-O-(CH ₂ ) _r -*,
*-(CH ₂ ) _p -C(=O)-O-(CH ₂ ) _q -O-C(=O)-(CH ₂ ) _r -*,
*-(CH ₂ ) _n1 -O-C(=O)-(CH ₂ ) _n2 -C(=O)-O-(CH ₂ ) _n3 -O-C(=O)-(CH ₂ ) _n4 -C(=O)-O-(CH ₂ ) _n5 -*,
*-(CH ₂ ) _n1 -C(=O)-O-(CH ₂ ) _n2 -O-C(=O)-(CH ₂ ) _n3 -C(=O)-O-(CH ₂ ) _n4 -O-C(=O)-(CH ₂ ) _n5 -*,
In the above structure, p, q, and r are each independently an integer of 1 to 6.
n1 to n5 are each independently an integer of 1 to 6. However, when n1 to n5 are each a divalent hydrocarbon group, the total number of carbon atoms is 20 or less.
* represents a bond. 2. The liquid crystal aligning agent according to claim 1, wherein the diamine (A) is at least one diamine selected from the group consisting of the following formulae (d _A -1) to (d _A -10):
(In the formulae (d _A -1) to (d _A -10), the hydrogen atoms on the benzene rings may be substituted with monovalent substituents. p, q, and r each independently represent an integer of 1 to 6. n1 to n5 each independently represent an integer of 1 to 6. However, in the case of n1 to n5, the total number of carbon atoms in the divalent hydrocarbon groups is 20 or less.) The liquid crystal aligning agent according to claim 1, wherein the liquid crystal aligning agent contains the following polymer (B) and/or the following polymer (C):
Polymer (B): At least one polymer (PB) selected from the group consisting of polyimide precursors obtained using a diamine component containing diamine (B) represented by the following formula ( _dAL ) (excluding those included in the diamine ( _A )), and polyimides which are imidized products of the polyimide precursors:
However, when a diamine other than the diamine (B) is contained as the diamine component, the diamine (A) is not contained. Also, when a diamine other than the diamine (B) is contained as the diamine component and the diamine (C) is contained, the amount of the diamine (C) used is less than 30 mol % of the total diamine components.
In formula (d _AL ), Ar ₁ and Ar _1′ each independently represent a benzene ring, a biphenyl structure, or a naphthalene ring, and one or more hydrogen atoms on the benzene ring, the biphenyl structure, or the naphthalene ring may be substituted with a monovalent group.
_L1 and L1 _' each independently represent a single bond, -O-, -C(=O)-, or -O-C(=O)-. A represents _-CH2- , an alkylene group having 2 to 12 carbon atoms, or a divalent organic group in which at least one of -O-, -C(=O)-O-, and -O-C(=O)- is inserted between the carbon-carbon bonds of the alkylene group. Any hydrogen atom possessed by A may be substituted with a halogen atom.
However, when L ₁ and L _1′ in formula (d _AL ) are —O—, A represents —CH ₂ —, an alkylene group having 2 to 12 carbon atoms, or a divalent organic group formed by inserting —O— between the carbon-carbon bonds of the alkylene group.
Z represents a hydrogen atom or a monovalent organic group. Multiple Zs may be the same or different.
Polymer (C): At least one polymer (P C ) selected from the group consisting of polyimide precursors obtained using diamine components containing diamine ( _C ) represented by the following formula (d _n ) in an amount of 30 mol % or more of the total diamine components, and polyimides which are imidized products of the polyimide precursors:
However, when a diamine other than the diamine (C) is contained as the diamine component, the diamine (A) is not contained.
In formula (d _n ), Y represents an aromatic ring having a nitrogen atom-containing heterocycle and an amino group represented by the group "*21-NR-*22" (where *21 and *22 represent bonds bonded to carbon atoms constituting the aromatic ring).
The carbon atom does not form a ring with the nitrogen atom to which R is attached.
R represents a hydrogen atom or a monovalent organic group, and the monovalent organic group is bonded to the nitrogen atom at a carbon atom other than the carbonyl carbon.
Z represents a hydrogen atom or a monovalent organic group. Multiple Zs may be the same or different. The liquid crystal aligning agent according to claim 4, wherein the liquid crystal aligning agent contains the polymer (B) and the polymer (C). The liquid crystal aligning agent according to claim 4, wherein the polymer (B) is obtained by a polycondensation reaction between the diamine component and a tetracarboxylic acid component containing an acyclic aliphatic tetracarboxylic acid dianhydride, an alicyclic tetracarboxylic acid dianhydride, an aromatic tetracarboxylic acid dianhydride, or a derivative thereof. The liquid crystal aligning agent according to claim 4, wherein the polymer (C) is obtained by a polycondensation reaction between the diamine component and a tetracarboxylic acid component containing an acyclic aliphatic tetracarboxylic acid dianhydride, an alicyclic tetracarboxylic acid dianhydride, an aromatic tetracarboxylic acid dianhydride, or a derivative thereof. The liquid crystal aligning agent according to claim 1, further comprising at least one additive component selected from the group consisting of crosslinking compounds having at least one substituent selected from an oxiranyl group, an oxetanyl group, a blocked isocyanate group, an oxazoline group, a cyclocarbonate group, a hydroxy group, and an alkoxy group, and crosslinking compounds having a polymerizable unsaturated group; a functional silane compound; a metal chelate compound; a curing accelerator; a surfactant; an antioxidant; a sensitizer; a preservative; and a compound for adjusting the dielectric constant or electrical resistance of the resulting liquid crystal alignment film. A liquid crystal alignment film obtained from the liquid crystal alignment agent described in any one of claims 1 to 8. A liquid crystal display element comprising the liquid crystal alignment film according to claim 9. The liquid crystal display element according to claim 10, which is a horizontal electric field liquid crystal display element. A method for manufacturing a liquid crystal display element, comprising the following steps (1) to (3):
Step (1): A step of applying the liquid crystal aligning agent according to any one of claims 1 to 8 onto a substrate; Step (2): A step of baking the applied liquid crystal aligning agent to obtain a film; Step (3): A step of performing an alignment treatment on the film obtained in Step (2).